# 42 Librae

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Star in the constellation Libra

42 Librae Observation data Epoch J2000.0 Equinox J2000.0 Constellation Libra Right ascension 15h 34m 16.89835s[1] Declination −10° 03′ 05.07536″[1] Apparent magnitude (V) 4.97[2] Characteristics Spectral type K3-III CN2[3] B−V color index 1.302±0.056[2] Astrometry Radial velocity (Rv) −21.8±2.8[2] km/s Proper motion (μ) RA: −16.872[1] mas/yr Dec.: −17.820[1] mas/yr Parallax (π) 8.7152±0.2628 mas[1] Distance 370 ± 10 ly (115 ± 3 pc) Absolute magnitude (MV) −0.37[2] Details Radius 25.9±0.4[1] R☉ Luminosity 213.6±7.3[1] L☉ Surface gravity (log g) 2.30[4] cgs Temperature 4,332±34[1] K Metallicity [Fe/H] −0.03±0.06[2] dex Other designations 42 Lib, CD−23°12458, FK5 3239, GJ 9526, HD 139663, HIP 76742, HR 5824, SAO 183686[5] Database references SIMBAD data

**42 Librae** is a single[6] [star](/source/Star) located around 370[1] [light years](/source/Light_year) distant from the Sun in the southern [zodiac](/source/Zodiac) [constellation](/source/Constellation) of [Libra](/source/Libra_(constellation)).[5] It is visible to the naked eye as a faint, orange-hued star with an [apparent visual magnitude](/source/Apparent_visual_magnitude) of 4.97.[2] This object is drifting closer to the Earth with a heliocentric [radial velocity](/source/Radial_velocity) of −22 km/s.[2]

The [Bayer designation](/source/Bayer_designation) Chi Librae has been associated with this star, despite [Johann Bayer](/source/Johann_Bayer) not marking it as such in his *[Uranometria](/source/Uranometria)*.[7] [Bode](/source/Johann_Elert_Bode) assigned the designation χ Librae to this star in his *Uranographia*.[8] The designation is no longer in use.

This is an aging [giant star](/source/Giant_star) with a [stellar classification](/source/Stellar_classification) of K3-III CN2,[3] where the suffix notation indicates this is a strong [CN star](/source/CN_star) with a high overabundance of [cyanogen](/source/Cyano_radical) in its [spectrum](/source/Stellar_spectrum). Having exhausted the supply of hydrogen at its [core](/source/Stellar_core), this star has expanded to 26 times the [Sun's radius](/source/Sun's_radius).[1] Within the [margin of error](/source/Margin_of_error) it has near-solar abundances of iron,[2] suggesting a Sun–like [metallicity](/source/Metallicity). The star is radiating 214[1] times the [luminosity of the Sun](/source/Luminosity_of_the_Sun) from its swollen [photosphere](/source/Photosphere) at an [effective temperature](/source/Effective_temperature) of 4,332 K.[1]

## References

1. ^ [***a***](#cite_ref-GaiaDR2_1-0) [***b***](#cite_ref-GaiaDR2_1-1) [***c***](#cite_ref-GaiaDR2_1-2) [***d***](#cite_ref-GaiaDR2_1-3) [***e***](#cite_ref-GaiaDR2_1-4) [***f***](#cite_ref-GaiaDR2_1-5) [***g***](#cite_ref-GaiaDR2_1-6) [***h***](#cite_ref-GaiaDR2_1-7) [***i***](#cite_ref-GaiaDR2_1-8) [***j***](#cite_ref-GaiaDR2_1-9) [***k***](#cite_ref-GaiaDR2_1-10) [***l***](#cite_ref-GaiaDR2_1-11) [Brown, A. G. A.](/source/Anthony_Brown_(scientist)); et al. ([Gaia collaboration](/source/Data_Processing_and_Analysis_Consortium)) (August 2018). ["*Gaia* Data Release 2: Summary of the contents and survey properties"](https://doi.org/10.1051%2F0004-6361%2F201833051). *[Astronomy & Astrophysics](/source/Astronomy_%26_Astrophysics)*. **616**. A1. [arXiv](/source/ArXiv_(identifier)):[1804.09365](https://arxiv.org/abs/1804.09365). [Bibcode](/source/Bibcode_(identifier)):[2018A&A...616A...1G](https://ui.adsabs.harvard.edu/abs/2018A&A...616A...1G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201833051](https://doi.org/10.1051%2F0004-6361%2F201833051). [Gaia DR2 record for this source](https://vizier.u-strasbg.fr/viz-bin/VizieR-S?Gaia%20DR2%206238537823914049408) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-Anderson2012_2-0) [***b***](#cite_ref-Anderson2012_2-1) [***c***](#cite_ref-Anderson2012_2-2) [***d***](#cite_ref-Anderson2012_2-3) [***e***](#cite_ref-Anderson2012_2-4) [***f***](#cite_ref-Anderson2012_2-5) [***g***](#cite_ref-Anderson2012_2-6) [***h***](#cite_ref-Anderson2012_2-7) Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", *Astronomy Letters*, **38** (5): 331, [arXiv](/source/ArXiv_(identifier)):[1108.4971](https://arxiv.org/abs/1108.4971), [Bibcode](/source/Bibcode_(identifier)):[2012AstL...38..331A](https://ui.adsabs.harvard.edu/abs/2012AstL...38..331A), [doi](/source/Doi_(identifier)):[10.1134/S1063773712050015](https://doi.org/10.1134%2FS1063773712050015), [S2CID](/source/S2CID_(identifier)) [119257644](https://api.semanticscholar.org/CorpusID:119257644).

1. ^ [***a***](#cite_ref-perkins1989_3-0) [***b***](#cite_ref-perkins1989_3-1) Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", *Astrophysical Journal Supplement Series*, **71**: 245, [Bibcode](/source/Bibcode_(identifier)):[1989ApJS...71..245K](https://ui.adsabs.harvard.edu/abs/1989ApJS...71..245K), [doi](/source/Doi_(identifier)):[10.1086/191373](https://doi.org/10.1086%2F191373).

1. **[^](#cite_ref-McWilliam1990_4-0)** McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", *Astrophysical Journal Supplement Series*, **74**: 1075–1128, [Bibcode](/source/Bibcode_(identifier)):[1990ApJS...74.1075M](https://ui.adsabs.harvard.edu/abs/1990ApJS...74.1075M), [doi](/source/Doi_(identifier)):[10.1086/191527](https://doi.org/10.1086%2F191527).

1. ^ [***a***](#cite_ref-SIMBAD_5-0) [***b***](#cite_ref-SIMBAD_5-1) ["42 Lib"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=42+Lib). *[SIMBAD](/source/SIMBAD)*. [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved 2019-07-17.

1. **[^](#cite_ref-Eggleton2008_6-0)** Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", *Monthly Notices of the Royal Astronomical Society*, **389** (2): 869–879, [arXiv](/source/ArXiv_(identifier)):[0806.2878](https://arxiv.org/abs/0806.2878), [Bibcode](/source/Bibcode_(identifier)):[2008MNRAS.389..869E](https://ui.adsabs.harvard.edu/abs/2008MNRAS.389..869E), [doi](/source/Doi_(identifier)):[10.1111/j.1365-2966.2008.13596.x](https://doi.org/10.1111%2Fj.1365-2966.2008.13596.x), [S2CID](/source/S2CID_(identifier)) [14878976](https://api.semanticscholar.org/CorpusID:14878976).

1. **[^](#cite_ref-bayer_7-0)** Bayer, Johann; Mair, Alexander (1603). [*Uranometria*](https://books.google.com/books?id=5NrCIF5mnysC&dq=bayer+uranometria&pg=IA1) (in Latin). Excvdit Christophorvs Mangvs. Retrieved 2025-11-10.

1. **[^](#cite_ref-bode_8-0)** Bode, Johann (1801). [*Uranometria*](https://www.google.co.uk/books/edition/Allgemeine_Beschreibung_und_Nachweisung/NUlRAAAAcAAJ?hl=en&gbpv=1&dq=bode&printsec=frontcover) (in German). Selbstverl. p. 57. Retrieved 2026-01-21.

v t e Constellation of Libra List of stars in Libra Libra in Chinese astronomy Stars Bayer α1 α2 (Zubenelgenubi) β (Zubeneschamali) γ (Zubenelhakrabi) δ ε ζ1 ζ2 ζ3 ζ4 η θ ι1 ι2 κ λ μ ν ξ1 ξ2 ο σ (Brachium) τ υ Flamsteed 2 3 4 5 10 11 12 16 17 18 22 23 26 28 30 36 37 41 42 47 48 49 50 Variable HN HO KU KX HR 5504 5455 HD 133131 134439 134440 135485 137010 139139 140283 141569 141937 Other 2M1510 2MASS 1507−1627 CWISEP J1446−2317 HE 1523−0901 WASP-57 WISE 1534−1043 WISE 1541−2250 Exoplanets 23 Librae b c Gliese 581b c e HD 137010 b (unconfirmed) K2-315b WASP-189b Star clusters NGC 5897 Galaxies NGC 5597 5605 5716 5728 5792 5793 5861 5885 5890 5898 5915 5917 Other AP Librae IC 1059 IRAS 14348−1447 PKS 1510−089 PKS 1519−273 QSO B1524−136 RXC J1504.1−0248 BCG Category

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Adapted from the Wikipedia article [42 Librae](https://en.wikipedia.org/wiki/42_Librae) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/42_Librae?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.